A cleaning device for a coal chemical gasification wastewater heat exchange unit

Abstract

The utility model relates to a kind of cleaning device of coal chemical gasification wastewater heat exchange unit, belong to coal chemical wastewater heat exchange field, including heat exchange unit, waste residue filter and high-pressure flushing pump;The inlet of high-pressure flushing pump is communicated with the outlet of cleaning liquid tank, the outlet of high-pressure flushing pump is connected at the outlet of heat exchange unit by infusion pipeline, first stop valve is provided on infusion pipeline, the inlet of heat exchange unit is connected at the inlet of waste residue filter by drainage pipeline, second stop valve is provided on drainage pipeline, the filtrate outlet of waste residue filter is communicated with the first inlet of cleaning liquid tank.The utility model solves the problem that heat exchanger in gasification wastewater heat exchange unit is easy to block, maintenance frequently, realizes gasification wastewater stable cooling and long-period high-efficiency operation.

Description

Technical Field

[0001] This utility model belongs to the field of heat exchange for coal chemical wastewater, specifically a cleaning device for a coal chemical gasification wastewater heat exchange unit. Background Technology

[0002] Coal chemical production involves numerous heat exchange operations with high-temperature, high-pressure, flammable, explosive, and corrosive media. Coal and oxygen (or steam) undergo a partial oxidation reaction at high temperatures in the gasifier to produce syngas (mainly composed of CO and H2). Minerals in the coal (such as ash) and unreacted carbon melt at high temperatures, forming liquid ash slag, which ultimately becomes gasification wastewater. This wastewater contains a large amount of fine ash, chloride ions, high hardness, and a large amount of suspended solids such as reagent residues. Upon entering the heat exchanger (during heating or cooling), these solids crystallize and precipitate on the inner surface of the heat exchange tubes. These precipitates combine with the suspended solids on the inner wall of the heat exchange tubes to form a large amount of scale, affecting heat exchange efficiency and causing the heat exchanger to become clogged and scaled within a short period of operation.

[0003] Gasification wastewater has a significant impact on the performance and reliability of heat exchangers. When the wastewater heat exchanger becomes clogged, the wastewater treatment system is forced to operate with reduced circulation, thereby disrupting the system's water balance. Wastewater containing ammonia nitrogen and chloride ions is not discharged in time, and the amount of fresh water added is insufficient, leading to the accumulation of substances such as ammonia nitrogen and chloride ions in the system, which affects long-term stable operation.

[0004] Therefore, improving the heat exchange efficiency of heat exchange units is necessary to further reduce energy consumption, increase production efficiency, reduce equipment maintenance frequency, and thus lower production costs. To address this issue, technicians typically need to disconnect the heat exchanger for offline physical cleaning. This cleaning process requires disassembling and reassembling the heat exchanger heads, resulting in lengthy cleaning times. Furthermore, the use of high-pressure water jets for cleaning can lead to incomplete cleaning and damage to the heat exchanger tubes, potentially causing leaks during operation. Currently, there are also related heat exchanger cleaning devices, such as the utility model patent "A Heat Exchanger Cleaning Device" with application number 201921314041.2. The heat exchanger has a chemical inlet at the lower end and a chemical outlet at the upper end. The chemical cleaning device includes a chemical tank, a chemical cleaning machine, and a chemical dosing pipeline. The chemical dosing pipeline includes a chemical inlet pipeline and a chemical outlet pipeline. The chemical tank, chemical cleaning machine, chemical inlet pipeline, chemical outlet pipeline, and heat exchanger form a circulation system. Cleaning ball valves are installed on both the chemical inlet and outlet pipelines. Although this allows the heat exchanger to be cleaned without disassembly or installation, reducing labor and cleaning agents, it is not suitable for the daily cleaning of heat exchanger units used in coal chemical gasification wastewater treatment. Utility Model Content

[0005] In view of the problems existing in the prior art, this utility model provides a cleaning device for a coal chemical gasification wastewater heat exchanger unit, which solves the problems of easy clogging and frequent maintenance of heat exchangers in the gasification wastewater heat exchanger unit, and realizes stable cooling of gasification wastewater and long-term high-efficiency operation.

[0006] This utility model is achieved through the following technical solution:

[0007] A cleaning device for a coal chemical gasification wastewater heat exchanger unit includes a heat exchanger unit, a waste residue filter, and a high-pressure flushing pump;

[0008] The inlet of the high-pressure flushing pump is connected to the outlet of the cleaning liquid tank. The outlet of the high-pressure flushing pump is connected to the outlet of the heat exchange unit through a liquid delivery pipeline. A first shut-off valve is installed on the liquid delivery pipeline. The inlet of the heat exchange unit is connected to the inlet of the waste residue filter through a drain pipeline. A second shut-off valve is installed on the drain pipeline. The filtrate outlet of the waste residue filter is connected to the first inlet of the cleaning liquid tank.

[0009] Preferably, the high-pressure flushing pump and the cleaning fluid tank are installed on the ground, with the cleaning fluid tank located on one side of the high-pressure flushing pump and the heat exchange unit located above the other side of the high-pressure flushing pump.

[0010] Furthermore, the infusion pipeline has an L-shaped structure, with the bottom of the vertical section connected to the outlet of the high-pressure flushing pump, and one end of the horizontal section connected to the outlet pipe of the heat exchanger unit.

[0011] Furthermore, the second inlet of the cleaning fluid tank is connected to the outlet of the return pipe, the inlet of the return pipe is connected to the drain port on one side of the vertical section of the infusion pipeline, the drain port is located between the high-pressure flushing pump and the first shut-off valve, and a third shut-off valve is installed on the return pipe.

[0012] Furthermore, the first shut-off valve is located on the horizontal section of the infusion pipeline, and the first shut-off valve is set on the vertical section away from the infusion pipeline. A fourth shut-off valve is set on the outlet pipe of the heat exchange unit, and the fourth shut-off valve is located below the first shut-off valve.

[0013] Furthermore, the cleaning fluid tank is located on one side of the heat exchanger unit inlet, and the waste residue filter is higher than the heat exchanger unit and located between the cleaning fluid tank and the heat exchanger unit inlet.

[0014] Furthermore, the drain pipe is a horizontal structure. The inlet end of the drain pipe is connected to the drain port on one side of the inlet pipe of the heat exchanger unit, and the outlet end of the drain pipe is connected to the inlet of the waste residue filter. A fifth shut-off valve is installed on the inlet pipe of the heat exchanger unit, and the fifth shut-off valve is located above the second shut-off valve.

[0015] Preferably, the filtrate outlet of the waste residue filter is connected to the first inlet of the cleaning liquid tank through a filtrate delivery pipeline, and a sixth shut-off valve is installed on the filtrate delivery pipeline.

[0016] Furthermore, the filtrate outlet of the waste residue filter is located at the top of the waste residue filter, and the filter residue outlet is provided at the bottom of the waste residue filter. The filter residue outlet is connected to the inlet of the waste residue pipeline, and a seventh shut-off valve is installed on the waste residue pipeline.

[0017] Preferably, the inner wall of the heat exchange tube in the heat exchange unit is coated with a silicon dioxide or aluminum oxide nano-coating with a thickness of 2-3 μm.

[0018] Compared with the prior art, the present invention has the following beneficial technical effects:

[0019] This invention relates to a cleaning device for a heat exchanger unit used in coal chemical gasification wastewater treatment. First, the heat exchanger unit is isolated by closing its inlet and outlet. Then, by opening the first shut-off valve, a high-pressure flushing pump delivers cleaning solution from the cleaning liquid tank to the heat exchanger unit through a delivery pipeline. The cleaning solution performs a reverse fluid flushing of the inner wall of the heat exchanger tubes, removing the attached scale. By opening the second shut-off valve, the liquid containing waste residue after cleaning flows into the waste residue filter inlet through a drain pipeline. The filtrate filtered by the waste residue filter flows back into the cleaning liquid tank to continue its cleaning function, saving cleaning solution and improving cleaning efficiency. Cleaning is complete when the pressure difference between the inlet and outlet of the heat exchanger is less than a set value. This invention is highly efficient, anti-clogging, energy-saving, and reduces consumption, solving the problems of easy clogging and frequent maintenance in gasification wastewater heat exchanger units. This heat exchanger is suitable for cooling wastewater with high suspended solids, such as coal gasification wastewater, significantly improving heat exchange efficiency and system operational stability while saving costs. Under the premise of stable temperature and flow rate of gasification wastewater discharge, the operating time is increased from 60 days to over 180 days. The cleaning process can be automated, eliminating the need for manual isolation and removal of the end caps, thus meeting the urgent need for efficient and safe heat exchange equipment in coal chemical production. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating the cleaning process of the heat exchanger unit for coal chemical gasification wastewater as described in this utility model.

[0021] In the diagram: 1-Heat exchanger unit; 2-Cleaning liquid tank; 3-High-pressure flushing pump; 4-Waste residue filter; 5-First shut-off valve; 6-Second shut-off valve; 7-Third shut-off valve; 8-Fourth shut-off valve; 9-Fifth shut-off valve; 10-Sixth shut-off valve; 11-Seventh shut-off valve. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to specific embodiments. The description is for explanation and not limitation of the present invention.

[0023] This utility model relates to a cleaning device for a heat exchanger unit used in coal chemical gasification wastewater treatment, such as... Figure 1As shown, it includes a heat exchanger unit 1 and a cleaning unit. The cleaning unit includes a cleaning liquid tank 2, a waste residue filter 4, and a high-pressure flushing pump 3.

[0024] The inlet of the high-pressure flushing pump 3 is connected to the outlet of the cleaning fluid tank 2. The outlet of the high-pressure flushing pump 3 is connected to the outlet of the heat exchanger unit 1 via a liquid delivery pipeline. A first shut-off valve 5 is installed on the liquid delivery pipeline. The inlet of the heat exchanger unit 1 is connected to the inlet of the waste residue filter 4 via a drain pipeline. A second shut-off valve 6 is installed on the drain pipeline. The filtrate outlet of the waste residue filter 4 is connected to the first inlet of the cleaning fluid tank 2. In this way, the cleaning fluid after cleaning can continue to flow into the cleaning fluid tank 2 to continue its cleaning function, saving cleaning fluid and improving cleaning efficiency. Afterward, the cleaning fluid can be replaced with new cleaning fluid. The cleaning fluid uses a common acidic solution, with HCl and sodium polyacrylate as the solute and dispersant. The mass of HCl is 10% of the mass of the cleaning fluid, and the mass of sodium polyacrylate is 1% of the mass of the cleaning fluid (the amount of HCl and sodium polyacrylate can be adjusted according to the working conditions). The 10% HCl produces H2O. + This allows for the rapid removal of scale from the inner wall of the heat exchange tubes in heat exchanger unit 1. The 1% sodium polyacrylate prevents scale from re-agglomerating, enhancing the cleaning effect. It enables periodic or irregular flushing of the inner wall of the heat exchange tubes to remove adhering scale. Cleaning is considered complete when the pressure difference between the heat exchanger inlet and outlet is less than the set value.

[0025] The pressure difference between the inlet and outlet of heat exchanger unit 1 is detected by pressure gauge PT03 at the inlet, pressure gauge PT04 at the outlet, and differential pressure gauge PDT02 between PT03 and PT04. The outlet temperature and flow rate are detected by temperature sensor (TT01) and flow sensor (FT01) at the outlet of heat exchanger unit 1 to determine the blockage status of the heat exchanger. If the pressure difference and temperature exceed set thresholds, or the flow rate falls below a set threshold, heat exchanger blockage is determined. A cascading logic system automatically starts the high-pressure flushing pump 3, simultaneously opening the first shut-off valve 5 and the second shut-off valve 6. Cleaning fluid is then injected into the heat exchanger's flow path through the high-pressure flushing pump 3 for backwashing. Cleaning is considered complete when the pressure difference between the inlet and outlet of the heat exchanger is less than the set value of 0.2 MPa.

[0026] As a preferred embodiment, the filtrate outlet of the waste residue filter 4 of this utility model is located at the top of the waste residue filter 4, and a filter residue outlet is further provided at the bottom of the waste residue filter 4. The filter residue outlet is connected to the inlet of the waste residue pipeline, and a shut-off valve is installed on the waste residue pipeline. Figure 1 The seventh shut-off valve is 11. When the amount of sludge filtered by the waste sludge filter 4 is large during the cleaning process, the pressure gauge PT01 at the outlet of the waste sludge filter 4, the pressure gauge PT02 at the inlet, and the differential pressure gauge PDT01 between PT01 and PT02 are used to determine whether the pressure difference between the inlet and outlet of the waste sludge filter 4 is greater than 50 kPa. The seventh shut-off valve 11 is then opened through an interlocking logic to discharge the sludge.

[0027] Generally, the high-pressure flushing pump 3 and the cleaning fluid tank 2 are fixed on the ground, with the cleaning fluid tank 2 located on one side of the high-pressure flushing pump 3 and the heat exchange unit 1 located above the other side of the high-pressure flushing pump 3. The fluid delivery pipeline is L-shaped, with the bottom of its vertical section connected to the outlet of the high-pressure flushing pump 3 and one end of its horizontal section connected to the outlet pipe of the heat exchange unit 1.

[0028] To facilitate reflux and protect the high-pressure flushing pump 3, a reflux pipe is further configured. The outlet of the reflux pipe is connected to the second inlet of the cleaning fluid tank 2, and the inlet of the reflux pipe is connected to the drain port on one side of the vertical section of the delivery pipeline. This drain port is located between the high-pressure flushing pump 3 and the first shut-off valve 5. A third shut-off valve 7 is installed on the reflux pipe. Specifically, the first shut-off valve 5 is installed on the horizontal section of the delivery pipeline and is located away from the vertical section of the delivery pipeline. A fourth shut-off valve 8 is installed on the outlet pipe of the heat exchanger unit 1, located below the first shut-off valve 5, so that the normal flow of cleaning fluid in the delivery pipeline is not affected when the outlet of the heat exchanger unit 1 is closed.

[0029] In this invention, the cleaning fluid tank 2 is located on one side of the inlet of the heat exchanger unit 1, and the waste residue filter 4 is higher than the heat exchanger unit 1, positioned between the cleaning fluid tank 2 and the inlet of the heat exchanger unit 1. The drain pipe is horizontally designed, with its inlet end connected to the drain port on one side of the inlet pipe of the heat exchanger unit 1, and its outlet end connected to the inlet of the waste residue filter 4. A fifth shut-off valve 9 is installed on the inlet pipe of the heat exchanger unit 1, located above the second shut-off valve 6, so that when the inlet of the heat exchanger unit 1 is closed, the flow of cleaning fluid from the heat exchanger unit 1 to the waste residue filter 4 is not affected.

[0030] The filtrate outlet of the waste residue filter 4 is connected to the first inlet of the cleaning liquid tank 2 through the filtrate delivery pipeline. A sixth shut-off valve 10 is installed on the filtrate delivery pipeline to facilitate the control of the flow of the cleaning liquid into the cleaning liquid tank 2 after cleaning. Specific Implementation Example 1

[0032] like Figure 1 As shown, the wastewater discharged under the aerospace pulverized coal pressurized gasification process is taken as an example:

[0033] The discharged gasification wastewater has a flow rate FI01 ≥ 300 m³ / h 3 The water flowing through the fifth shut-off valve 9 into heat exchanger unit 1 under the condition of / h exchanges heat with the low-temperature medium (such as circulating water) on the other side. The low-temperature medium and the discharged wastewater exchange heat in a counter-current manner through heat exchanger unit 1 before entering the pipeline network. Initially, the outlet water temperature TI01 of the heat exchanger is ≤40℃, and the pressure difference between the inlet and outlet of the heat exchanger is ≤0.25MPa. According to the time control mode, the cleaning device of this utility model is cleaned once every 15 days by default, and each time it operates according to the following process:

[0034] Close the first shut-off valve 5. After starting the high-pressure flushing pump 3 through the interlock logic, open the third shut-off valve 7. The cleaning liquid first flows back counterclockwise in the high-pressure flushing pump 3, then close the fourth shut-off valve 8 and the fifth shut-off valve 9 to isolate the heat exchange unit 1. After the reflux is completed, open the first shut-off valve 5 and the second shut-off valve 6. After closing the third shut-off valve 7, the cleaning liquid flows into the heat exchanger for acid cleaning to achieve reverse fluid flushing;

[0035] During the cleaning process, when the pressure difference between the inlet and outlet of the waste residue filter 4 is greater than 50 KPa, close the first shut-off valve 5 to suspend the inlet of the cleaning liquid, and control the opening of the seventh shut-off valve 11 through the interlock logic to discharge the waste residue through the waste residue pipeline;

[0036] When the pressure difference between the inlet and outlet of the heat exchanger is less than 0.2 MPa and the cleaning is detected to be qualified, control the closing of the first shut-off valve 5 and the second shut-off valve 6 through the interlock logic, open the fourth shut-off valve 8 and the fifth shut-off valve 9, and the heat exchanger is put into use. After completion, control the closing of the high-pressure flushing pump 3 through the interlock logic, and then open the seventh shut-off valve 11 to discharge the waste residue after cleaning. Specific Embodiment 2

[0038] As a preferred solution, the heat exchange tubes in the heat exchanger are made of corrosion-resistant alloys (such as 316L stainless steel, titanium alloy), and a silicon dioxide or aluminum oxide nano-coating with a thickness of 2 - 3 μm is coated on the inner wall. This coating has good film-forming properties, can be tightly combined with the metal surface, and is not easy to fall off, significantly improving the surface finish, hardness, and corrosion resistance of the inner surface of the heat exchange tubes, enhancing the pressure resistance, corrosion resistance, and anti-scaling ability. At the same time, this coating can withstand a maximum temperature of 600 °C, fully meeting the temperature requirements of coal chemical gasification wastewater.

[0039] Based on the above considerations, a heat exchanger made of titanium alloy is selected, and a silicon dioxide nano-coating with a thickness of 3 μm is coated on its inner wall to obtain a new heat exchange unit.

[0040] See Figure 1 As shown, the discharged wastewater obtained under the aerospace pulverized coal pressurized gasification process enters the new heat exchange unit through the fifth shut-off valve 9 under the condition of a flow rate FI01 ≥ 300 m 3 / h to exchange heat with the circulating water on the other side. The circulating water and the discharged wastewater enter the pipe network after countercurrent heat exchange in the new heat exchange unit.

[0041] Initially, the water temperature TI01 at the outlet of the heat exchanger ≤ 40 °C, and the pressure difference between the inlet and outlet of the heat exchanger ≤ 0.25 MPa. When the flow rate of the discharged wastewater FI01 < 300 m 3If any one of the following three parameters (not limited to one) occurs (i.e., the heat exchanger outlet water temperature TI01 > 40℃ and the heat exchanger inlet and outlet pressure difference PDT02 > 0.25MPa), the cleaning device of this utility model will operate according to the process of specific embodiment 1. Therefore, this embodiment is a conditional control mode, which can operate when any one of the following occurs during the operation of the heat exchanger: high inlet and outlet pressure difference, high outlet temperature (TI01), and low outlet flow rate (FI01).

[0042] Suspended solids deposition rate is reduced by 60%, continuous operation cycle of a single unit is extended from the traditional 60 days to over 180 days, heat transfer coefficient is increased by 2-3 times compared to traditional shell-and-tube heat exchangers, and the temperature of discharged wastewater can be stably reduced to below 40℃, while reducing circulating water consumption by approximately 1000 m³. 3 / h.

Claims

1. A cleaning device for a coal chemical gasification wastewater heat exchanger unit, characterized in that, It includes a heat exchanger unit (1), a waste residue filter (4), and a high-pressure flushing pump (3); The inlet of the high-pressure flushing pump (3) is connected to the outlet of the cleaning liquid tank (2). The outlet of the high-pressure flushing pump (3) is connected to the outlet of the heat exchange unit (1) through a liquid delivery pipeline. A first shut-off valve (5) is installed on the liquid delivery pipeline. The inlet of the heat exchange unit (1) is connected to the inlet of the waste residue filter (4) through a drain pipe. A second shut-off valve (6) is installed on the drain pipe. The filtrate outlet of the waste residue filter (4) is connected to the first inlet of the cleaning liquid tank (2).

2. The cleaning device for the coal chemical gasification wastewater heat exchange unit according to claim 1, characterized in that, The high-pressure flushing pump (3) and the cleaning fluid tank (2) are installed on the ground. The cleaning fluid tank (2) is located on one side of the high-pressure flushing pump (3), and the heat exchange unit (1) is located above the other side of the high-pressure flushing pump (3).

3. The cleaning device for the coal chemical gasification wastewater heat exchange unit according to claim 2, characterized in that, The infusion pipeline is an L-shaped structure. The bottom of the vertical section of the infusion pipeline is connected to the outlet of the high-pressure flushing pump (3), and one end of the horizontal section is connected to the outlet pipe of the heat exchanger unit (1).

4. The cleaning device for the coal chemical gasification wastewater heat exchange unit according to claim 3, characterized in that, The second inlet of the cleaning fluid tank (2) is connected to the outlet of the return pipe, the inlet of the return pipe is connected to the drain port on one side of the vertical section of the infusion pipeline, the drain port is located between the high-pressure flushing pump (3) and the first shut-off valve (5), and a third shut-off valve (7) is provided on the return pipe.

5. The cleaning device for the coal chemical gasification wastewater heat exchange unit according to claim 3, characterized in that, The first shut-off valve (5) is located on the horizontal section of the infusion pipeline and is set away from the vertical section of the infusion pipeline. A fourth shut-off valve (8) is set on the outlet pipe of the heat exchange unit (1) and is located below the first shut-off valve (5).

6. The cleaning device for the coal chemical gasification wastewater heat exchanger unit according to claim 2, characterized in that, The cleaning fluid tank (2) is located on one side of the inlet of the heat exchanger unit (1), and the waste residue filter (4) is higher than the heat exchanger unit (1) and located between the cleaning fluid tank (2) and the inlet of the heat exchanger unit (1).

7. The cleaning device for the coal chemical gasification wastewater heat exchange unit according to claim 6, characterized in that, The drain pipe is a horizontal structure. The inlet end of the drain pipe is connected to the drain port on one side of the inlet pipe of the heat exchanger (1). The outlet end of the drain pipe is connected to the inlet of the waste filter (4). A fifth shut-off valve (9) is installed on the inlet pipe of the heat exchanger (1). The fifth shut-off valve (9) is located above the second shut-off valve (6).

8. The cleaning device for the coal chemical gasification wastewater heat exchange unit according to claim 1, characterized in that, The filtrate outlet of the waste residue filter (4) is connected to the first inlet of the cleaning liquid tank (2) through a filtrate delivery pipe, and a sixth shut-off valve (10) is installed on the filtrate delivery pipe.

9. The cleaning device for the coal chemical gasification wastewater heat exchange unit according to claim 8, characterized in that, The filtrate outlet of the waste residue filter (4) is located at the top of the waste residue filter (4), and the filter residue outlet is provided at the bottom of the waste residue filter (4). The filter residue outlet is connected to the inlet of the waste residue pipeline, and a seventh shut-off valve (11) is installed on the waste residue pipeline.

10. The cleaning device for the coal chemical gasification wastewater heat exchange unit according to claim 1, characterized in that, The inner wall of the heat exchange tube in the heat exchange unit (1) is coated with a silicon dioxide or aluminum oxide nano-coating with a thickness of 2-3 μm.

Images